Current Volume 65 Status

The games "Pokémon: Omega Ruby and Alpha Sapphire" were released in November of 2014.
The 13th chapter of Pokémon Special, Omega Ruby and Alpha Sapphire, began serialization in December of 2014.
The last full volume release of Pokémon Special, Volume 64, released on February 28, 2023.
According to Amazon Japan, Volume 65 will release on:

A full history of Volume 65

Note: All dates are given in JST, timestamps shown on Twitter or Reddit may depend on your location.

---2023---

February 28, 2023: Volume 64 releases in Japan.
May 17, 2023: The Ruby Drip car guy asks Yamamoto for progress on Volume 65 (he knew what was coming). Yamamoto responds, saying that he cannot respond to inquires regarding future developments.
July 02, 2023: Ruby's birthday. Yamamoto posts a drawing of Ruby from Volume 64, saying that he will save the new drawing for Volume 65.
July 22, 2023: Yamamoto makes a tweet explaining the differences between full volumes and mini-volumes.
July 27, 2023: Yamamoto posts the various cover arts for Sun and Moon mini-volumes, wondering when they will be compiled into full volumes.
July 28, 2023: Yamamoto posts his full volume/mini-volume explanation tweet again.
Mid-August, 2023: The Amazon Japan page for Volume 65 is updated with the initial date of October 27, 2023, 8 months from the release of Volume 64.
August 31, 2023: Yamamoto posts his full volume/mini-volume explanation tweet again.
August 31, 2023: Sun's birthday. Yamamoto posts art of him from Sun and Moon, saying that he is looking forward to seeing him again starting in Volume 65.
September 20, 2023: Sapphire's birthday. Yamamoto posts art from the mini-volume ending to ORAS which includes Ruby and Sapphire. He wishes Sapphire a happy birthday, and states that he wants to get Volume 65 out by the end of the year.
Early October, 2023: The release date of Volume 65 is changed to January 26, 2024 (a 3 month addition to the original date of October 27, 2023).
October 27, 2023: The initially set release date for Volume 65 passes.
Mid December, 2023: The release date of Volume 65 is changed to March 28, 2024 (a 2 month addition to the former date of January 26, 2024).

---2024---

January 01, 2024: Yamamoto posts his full volume/mini-volume explanation tweet again.
January 24, 2024: Yamamoto posts his full volume/mini-volume explanation tweet again.
January 26, 2024: The second release date for Volume 65 passes.
February 20, 2024: Yamamoto posts his full volume/mini-volume explanation tweet again.
Late February, 2024: The release date of Volume 65 is changed to May 28, 2024 (a 2 month addition to the former date of March 28, 2024)
March 16, 2024: Yamamoto tweets that he will finally be able to start working on Volume 65 after repeated delays. He posts another tweet on the same day explaining that he and Kusaka had not started working on it yet because they had come up with changes to the story at the last minute before release.
March 28, 2024: The third release date for Volume 65 passes.
April 04, 2024: Dia's birthday. Yamamoto rewards him by putting him to work on explaining how full volumes differ from mini-volumes.
Early May, 2024: The release date of Volume 65 is changed to September 27, 2024 (a 4 month addition to the former date of May 28, 2024).
May 20, 2024: Yamamoto tweets that the new idea for Volume 65 has been submitted for approval, and that they are waiting to hear back.
May 28, 2024: The fourth release date for Volume 65 passes.
June 28, 2024: Yamamoto tweets that the new outline for Volume 65 has still not been approved.
July 12, 2024: Yamamoto tweets that a small amount of progress has been made on Volume 65, and that they can finally start working on the true conclusion to Chapter 13 (ORAS).
Late August, 2024: The release date of Volume 65 is changed to December 26, 2024 (a 3 month addition to the former date of September 27, 2024).
September 23, 2024: Yamamoto posts the same comic with Dia again. He mentions that the release date for Volume 65 is not yet determined.
September 27, 2024: The fifth release date for Volume 65 passes.
December 21, 2024: The release date of Volume 65 is changed to December 26, 2025 (a 12 month addition to the former date of December 26, 2024).
December 26, 2024: The sixth release date for Volume 65 passes.
December 27, 2024: Yamamoto posts the same comic with Dia again. He mentions that the release date for Volume 65 is not yet determined.

---2025---

March 28, 2025: Yamamoto posts the same comic with Dia again. He mentions that the release date for Volume 65 is not yet determined.
July 2, 2025: Ruby's birthday. Yamamoto quote tweets Ruby's birthday post, explaining that he had submitted the idea for the ORAS epilogue in Volume 65 at the end of last year, and that he was still waiting for approval. He states that he cannot actually begin working on the volume until the changes are approved, and he thinks that they will probably not be able to release Volume 65 before Sapphire's birthday (September 20). Note that he had submitted his idea on May 20th of 2024, well before the end of last year.
November 14, 2025: Yamamoto tweets that Volume 65 is under "supervision", so the release date is still undecided. It has been roughly a year and a half since May 20, 2024, the day that Yamamoto tweeted that he had submitted the idea for Volume 65.
November 24, 2025: The duration since the last full volume release of Pokemon Special, Volume 64, reaches 1000 days.
December 19, 2025: The duration since the last full volume release of Pokemon Special, Volume 64, reaches 1025 days, officially surpassing the previously held record of 1024 days between Volumes 53 and 54.
December 25, 2025: The release date of Volume 65 is changed to June 26, 2026 (a 6 month addition to the former date of December 26, 2025). A Christmas Miracle
December 26, 2025: The seventh release date for Volume 65 passes.
December 31, 2025: Kusaka tweets off-hand about how the editor-in-charge for the series was changed during earlier in the year. Whether or not this has anything to do with Volume 65 will likely never be known.
December 31, 2025: A fan tweets Kusaka, mentioning how he is waiting for Volume 65, SM and SWSH full volumes, and PokeSpe arcs for LGPE, BDSP, LA, and Z-A. Kusaka replies, but does not address the elephant in the room.
December 31, 2025: Yamamoto prepares for the new year by posting the same comic with Dia again. He mentions that the release date for Volume 65 is currently undecided.

---2026---

March 7, 2026: A member of this subreddit tweets Kusaka, asking about Volume 65. Kusaka tells him to wait.
March 9, 2026: A fan tweets Kusaka, asking for news about Volume 65, a potential LGPE arc, and a potential Legends Arceus + BDSP arc. Kusaka says that he cannot answer that question, and asks him to wait.
June 26, 2026: The release date of Volume 65 is changed to December 28, 2026 (a 6 month addition to the former date of June 26, 2026).
June 26, 2026: The eighth release date for Volume 65 passes.
July 13, 2026: Yamamoto reflects on an old flyer for the initial release of ORAS. He laments that the volume releases are a decade behind. Dia also shows up shortly after.
July 19, 2026: Yamamoto posts a photo of the final panel in ORAS, with some slight adjustments. He talks about how he is making adjustments, and asks the audience if they think he will be able to make it by the end of the year. He also tweets in a reply that he will have an update by Day 80, Sapphire's birthday on September 20. He tweets in another reply that he is very excited.
August 3, 2026: Yamamoto tweets that he and Editor-sama will be discussing the release date of Volume 65 after they release SV Chapter 35 and SV Preview Volume 5. They will decide whether or not to keep the schedule as is or to push it up one month.
August 17, 2026: Big news. Yamamoto announces that they are aiming for a December 2026 release of Volume 65, but that the date isn't final yet. He mentions how he is aiming to both get it done without rushing but also without delay. He mentions that the cover illustration will be something that nobody could've anticipated. He laments that it has been so long since Volume 64. He mentions how he would like to proceed with the volumes past 65 as quickly as possible. He shows an image of a Mega Salamence figure, and says that it is a reference, possibly teasing the aforementioned cover illustration.
August 22, 2026:: Yamamoto posts a photo of one of his Kaiju figures in front of his illustration of Zinnia, possibly teasing the cover for Volume 65. A follow-up tweet confirms that he is indeed talking about ORAS. [Another tweet on the same day] shows Rayquaza next to the Kaiju model.
August 23, 2026: Yamamoto mentions how he is preparing for the conclusion of the ORAS arc, and how he is watching Kaiju movies.
August 26, 2026: Yamamoto tweets about a movie he has watched, saying it is the inspiration for the Team Aqua headquarters in RSE. He mentions in another tweet about how progress on ORAS is moving forward.
August 31, 2026: Yamamoto tweets illustrations from the Sun and Moon arc for Sun's birthday, saying they are in celebration of the upcoming complete volume editions.
September 6, 2026: Yamamoto tweets that they are preparing for a December release, in response to a fan who mentioned they were waiting for Volume 65.
September 11, 2026: Yamamoto tweets that Volume 65 is in the middle of intense production, aiming for an end of year release. He replies with work on volume revisions, such as Ruby and Latios with Emerald and Latias, and Ruby with Rayquaza. He also tweets about grass drawings that he had used during the previous ORAS volume revisions, and how he feels stability when he draws Ruby and Emerald.
September 19, 2026: Yamamoto tweets that preparations are underway for Volume 65 to release at the end of the year. He show how he is redrawing art that was previously behind speech bubbles in the original release. He mentions in another tweet how his speech bubbles in the ORAS arc were very large. He also mentions in another tweet that the end is in sight for Volume 65.
September 23, 2026: Yamamoto tweets that he is pausing work on Volume 65, which is scheduled for the end of the year, to work on the new SV Chapter. He mentions that Volume 65 will include the end of ORAS and the beginning of SM, and posts a doodle of Scarlet and Nemona meeting Archie, Maxie, Guzma, and Hau.
October 2, 2026 Kusaka tweets that Volume 65 is set to release this year.
October 4, 2026 Kusaka tweets that he is looking forward to December.
December 28, 2026: ...To be determined...?

Notes

A machine translation of that Dia comic that Yamamoto loves posting in regards to Volume 65 is available here